Grounding wiring device and contact structure



c. M. SMITH 3,237,145 GROUNDING WIRING DEVICE AND CONTACT STRUCTURE Feb. 22, 1966 Filed April 26. 1963 ATTORV Clarence M Sml WITNESSES y United States Patent 3,237,145 GROUNDING WIRING DEVICE AND CONTACT STRUCTURE Clarence M. Smith, Trumbull, Conn., assignor, by mesne assignments, to Westinghouse Electric Corporation, a corporation of Pennsylvania Filed Apr. 26, 1963, Ser. No. 275,972 3 Claims. (Cl. 339-14) The present invention relates to grounding wiring devices and more particularly to grounding connectors and contact structure therefor.

In a grounding connector or receptacle, power contacts and a grounding contact are each provided with one or more resilient arms disposed for conductively engaging the blades or prongs of a plug inserted into the connector. Assurance of good contact with a blade or prong is satisfactorily obtained if a pair of opposed resilient contact arms are employed and is further improved if three point contact is provided by use of three resilient arms on the contact. Continued good contact over the device life is enhanced if the contact arm or arms are limited in deflection by other cooperating device structure so that the arms are prevented from being overstressed during use.

In the interest of economy, it is preferable in many applications that a connector or receptacle contact be formed to its final structure from a single piece of conductive material. With this approach, welding or other expense creating securance steps are eliminated. Further, there are some applications where a single piece contact is particularly or exclusively useful, for example, where the cross-section of the connector pocket in which the contact arms are to be disposed is so restricted in size (by considerations such as overall design needs and under- Writers limitations on overall device size) as elfect-ively to prohibit the use of any contact except a single piece contact. I

Thus, there are distinct advantages associated with cooperative employment of a single piece contact in a connector if the contact structure originated from the same material piece meets all the usual requirements in the blade or prong engagement relation and particularly if such structure provides additional benefits such as the capacity to engage each of differently oriented plug blades. Accordingly, a wiring device of the present invention comprises an insulative housing in which a pair of elongated single piece power contacts and an elongated single piece grounding contact are disposed in respective insulatively partitioned pockets. The power contacts include elongated resilient arms extending from a common planar contact base portion and disposed for engaging blades of a parallel blade plug or the blades of a tandem blade plug. The grounding contact includes two resilient arms formed from a common base and spaced apart at a distance less than the thickness of a grounding prong so that the arms are urged apart with the grounding prong inserted therebetween. Although such contacts have special advantage as cooperatively employed in the described wiring device or connector, they can in general be employed in other connector or receptacle devices.

Therefore, it is an object of the invention to provide a novel wiring device or connector in which single piece contacts are employed to provide eflicient plug blade engagement.

Another object of the invention is to provide a novel wiring device or connector which employs single piece contacts in providing efficient engagement of the blades of either a parallel or a tandem blade plug.

A further object of the invention is to provide a novel single piece power contact which efficiently engages a blade of a parallel or a tandem blade plug.

An additional object of the invention is to provide a Patented Feb. 22, 1966 figure further shows a plug in alignment with the connector;

FIG. 3 is a view of the plug taken along the reference line HIIII of FIGURE 2;

FIG. 4 shows a front view of the connector of FIGS. 1 and 2 and is taken along the reference line IVIV of FIG. 2;

FIG. 5 shows a cross-section-of the connector of FIG. 1 taken along the reference line VV of FIG. 2;

FIG. 6 shows a plan view of an insulative retaining member employed in the connector of FIGS. 1 and 2 and it is taken along the reference line VIVI of FIG. 2;

FIGS. 7 and 8 show respectively longitudinal side and longitudinal edge views of a grounding contact employed in the connector of FIGS. 1 and 2;

FIGS. 9, 10 and 11 show respectively front end, longitudinal side and longitudinal edge views of a power contact employed in the connector of FIGS. 1 and 2; and

FIG. 12 shows a portion of the section of FIG. 5 with a power blade of a tandem blade plug in engagement with one of the connector contacts.

More specifically, there is shown in FIG. 1 a connector wiring device 20 having an insulative housing 22. A rearward side 24 of the housing 22 is provided with cord grip structure 26 for the purpose of attaching a cord (not shown) to the connector 20. The cord grip structure 26 includes a pair of cord clamps 28 which are movably secured to the housing 24 by means of an annular ring member 30 and which are tightened against an inserted cord by means of screws 32.

As shown-in FIGS. 2-5, the connector 20 further includes a pair of elongated power contacts 34 and 36 and an elongated grounding contact 38 for respectively engaging power blades 40 and 42 and grounding prong 44 of a plug 46. The plug 46 as illustrated in this case is comprised of parts similar to those employed in the connector 20 including an insulative body 47, an insulative retaining member 64 and an insulative cover 66. As shown in FIG. 4, a front-end wall 48 of the connector 20 is provided with a pair of power blade slots 50 and 52 and a grounding prong slot 54 for entry of the blades 40, 42 and prong 44 into the connector 20. The connector power contacts 34 and 36 and grounding contact 38 are disposed in respective elongated and insulatively partitioned pockets 56, 58 and 60 which in turn are in alignment with the slots 50, 52 and 54.

The connector 20 can be regarded as being elongated from the front to rearward end thereof, and accordingly the contact pockets 56, 58 and 60 are insulatively partitioned from each other in the lateral direction by material of the housing 22 along the length of the connector 20 and the pockets 56, 58 and 60. FIG. 5 shows the partitioning achieved across one region of the connector 20, namely, across the longitudinal (body) portions of the pockets 56, 58 and 60 provided within housing body 62.

Overall limitations on the lateral dimensioning of the connector 20 coupled with the preferred provision of lateral insulative partitioning between the respective pockets 56, 58 and 60 places a limitation upon the crosssectional size of the contact pockets 56, 5 8 and and, therefore, also upon the organization of the structure of the contacts 34, 36 and 38. In this case, each contact pocket 56, 58 and 60 is formed by the housing body member 62 in cooperation with the insulative retaining member 64 which is secured to the body 62 by suitable means (not shown) extended through opening 65 of the retaining member 64 and which further is enclosed within the housing 22 by the insulative cover member 66. In turn, the cover 66 is secured to the body 62 by fasteners (not shown) extended through openings 68 in the body 62 or by other suitable means.

The insulative retaining member 64 is provided with wire openings 70 aligned with each pocket 56, 58 and 60 and extending in the housing longitudinal direction for entry of respective wires of the aforementioned cord into the pockets 56, 58 or 60 and engagement with the power contacts 34 and 36 and the grounding contact 38 or other wire engagement structure connected to such contact. The manner in which the cover 66 and the insulative member 64 cooperate in providing facility in the Wiring process does not form a part of this invention, but additional information related thereto can be obtained in a copending application entitled Wiring Device filed on October 16, 1961, by George F. Hawkes, Jr., Serial No. 145,309 and assigned to the present assignee.

Especially in consequence of the limitation on pocket size, each of the contacts 34, 36 and 38 is provided with its functioning structure from a single piece of material of suitable thickness in such a manner as to be organized efliciently for fitting in the pockets 56, 58 and 60 while simultaneously providing multiple point engagement of inserted plug blades and prong without overstressing effects on the contacts 34, 36 and 38. Further, in the case of the power contacts 34 and 36, the structural organization provides for accommodation of either a tandem or a parallel power blade of a plug. Hence, eflicient plug and blade engagement is cooperatively provided by all of the contacts 34, 36 and 38 in the structural environment of a limited size housing. However, the contacts 34, 36 and 38 can be employed in applications other than those in which the housing size is a limiting factor.

More particularly, the elongated power contacts 34 and 36 (FIGS. 9-11) and the elongated grounding contact 38 (FIGS. 7 and 8) are each formed from an elongated and planar piece of starting material such as an alloy of copper. Each contact 34, 36 and 38 is preferably provided with integral wire engagement structure including an end terminal portion 72 or 74 disposed in longitudinal (retaining member) portion 57, 59 or 61 of the associated pocket 56, 58 or 60* and having a lateral opening 76 or 78 through which a wire engaging screw 80 is extended for engagement with a nut (not shown). However, separate wire engagement structure riveted or otherwise conductively secured to the contacts 34, 36 and 38 can be employed. Further, each contact 34, 36 and 38 is provided with blade or prong engagement structure including resilient arms 82, 84 and 86 or 88 and 90 disposed in the aforementioned body portion of the associated pocket 56, 58 or 60 and such structure can be laterally offset from the associated terminal portion 72 or 74 by means of a laterally extending portion 92 or 94. The portions 92 and 94 can also aid in holding the aforementioned nuts against turning as the screw or screws 80 are advanced or withdrawn for wire engagement or release purposes.

The contact arms 82, 84 and 86 of the power contacts 34 and 36 are separated by respective slots 96, 98 and 100 so as to assure relatively independent resilient blade engagement action on the part of these contact arms. Further, to provide for fitting in the limitedly cross-sectioned body pocket portions of the pockets 56 and 58, the contact arms 82, 84 and 36 are extended longitudinally frontward from a common base portion 102 which in turn is integral with the lateral portion 92. The contact arm 82 is generally coplanar with the base portion 102 whereas the contact arms 84 and 86 are irregularly shaped and formed so as to have end contact portions 104 and 106 disposed in spaced but generally confronting relation with end contact portion 108 of the contact arm 82. For this purpose, each contact arm 84 or 86 is provided with a first portion 110 disposed generally perpendicularly to the contact base portion 102 and extending longitudinally outwardly along the slot 96 or 98. End contact portions 104 and 106 are disposed in confronting but spaced relation with end contact portion 108 as previously described since they are turned inwardly toward each other in a plane parallel with base portion 102.

Respective cutout portions 112 facilitate resilient deflection of the contact end portions 104 and 106. In addition to the spacing between the confronting surfaces of the contact end portions 104 and 106 and 108, the contact end portion 108 can be dished outwardly as indicated by the reference character 114 for facilitating blade entry and engagement with the contact end. portions 104, 106 and 108. As is common practice, inwardly facing bumps 116 can be employed to index an inserted power blade in engaged relation. Each of the contact end portions 104 and 106 are preferably in slight acute angular relation to the base portion 102 so as to assure resilient blade engagement.

Edges 118 and 120 of the contact end portions 104 and 106 are spaced by the slot 100 so as to allow for engagement of a tandemly disposed plug blade by the contact 34 or 36. Such a blade can commonly be provided for example on a commercial 250 volt plug in perpendicular relation to the other power blade of the plug. The connector 20 thus is provided with the blade slot 50 in T-shaped form and insertion of tandem blade 41 (FIG. 12) through the slot 50 results in engagement thereof by the power contact 34.

In the case of a parallel blade 40 or 42, blade engagement by the power contact 34 or 36 is produced by resilient return forces of the contact end portions 104, 106 and 108 on opposite sides of the blade 40 or 42. In the case of the tandem blade 41, contact end portions 104 and 106 urge the blade 41 in a longitudinal direction toward the contact end portion 108 which in turn provides urging forces in the opposite direction. In order to prevent overstressing effects, the contact end portions 104 and 106 are limited in deflection by housing portions 122 and 124 (FIG. 5) and the contact end portion 108 is limited in its deflection by housing portion 126.

The grounding contact arms 88 and 90 of the grounding contact 38 are extended longitudinally outwardly from lateral portion 94 and such arms have a width dimension along the major portion of their length so as to be fittable in the body portion of the pocket 60. Adjacent the outer end of each arm 88 or 90 an end contact portion or 132 are disposed in generally perpendicular relation with the arms 88 and 90 so as to provide spaced. but confronting contact surfaces 134 and 136 for engagement with the grounding prong 44. Outwardly dished portions 138 and 140 can be employed to facilitate grounding prong entry. As a consequence of such entry, deflection of the grounding contact arms 88- and 90 along the width dimension thereof produces relatively strong resilient return engaging forces on the inserted plug prong 44. Grounding contact arm deflection is also limited to prevent overstressing effects, in this example by end surfaces 142 of grooves 144 of the housing 22 in which wing portions 146 of the grounding contact arms 88 and 90 are disposed. If desired, the terminal end portion 74 of the grounding contact 38 can be provided with a longitudinally extending arm 91 for the purpose of establishing a grounding connection with the ring 30 of the cord clamping structure 26. In order to fix the contacts 34, 36 or 33 in place in the assembled connector 20, wing portions 77 or 79, for example, can be disposed in housing grooves 81 in the insulative retaining member 64, as shown in FIG. 6. Leading edge portions 83 or 85 of the terminal end portion 72 or 74 can be employed to limit insertional movement of the contacts 34, 36 or 38 into the housing body 62. Securance of the insulative retaining member 64 to the body 62 then fixes the contacts 34, 36 and 38 in place for resilient operation of the respective blade or prong engaging arms of these contacts.

The foregoing description has been set forth only to illustrate the principles of the invention. Accordingly, it is desired that the invention be not limited by the embodiment or embodiments described, but, rather, that it be accorded an interpretation consistent with the scope and spirit of its broad principles.

What is claimed is:

1. A grounding wire female connector adaptable to receive either a parallel blade or a tanden blade plug, comprising an insulating housing having three longitudinally extending, parallel channels partitioned from each other in a lateral direction, a single piece elongated metal contact disposed in each of said channels, one of said contacts engageable With a plug grounding prong and having a pair of spaced apart, flat, elongated resilient arms extending longitudinally from a common metal base portion with the width dimension of said arms disposed in a common plane, each arm having respective end contact surfaces formed generally at right angles to the width dimension and confronting each other in spaced relation for engaging said grounding prong therebetween, each of the other two metal contacts having three, spaced apart resilient contact arms extending longitudinally from a common metal base portion, one arm being generally coplanar with said base portion, the other two arms being generally perpendicular with said base portion and said one arm, and parallel with each other, said two arms having extensions projecting inwardly towards each other in a spaced but confronting relation to each other and to said one arm to form a power contact channel for receiving a parallel blade or a tandem blade, said tandem blade partially engaged by the confronting extensions and said one arm in substantially perpendicular direction thereto, said parallel blade totally engaged inside the channel in a plane substantially parallel to the extensions and to said one arm, said two inwardly projecting arm extensions and said one arm firmly engaging either types of blade so as to force the extensions and arm against each other.

2. The female connector structure of claim 1 in which the face of the connector has at least one T-shaped. entrance aperture for receiving a parallel blade or a tandem blade.

3. The ground wire connector structure of claim 1 in which the inward extensions of the two contact arms are disposed at a small acute angle to the plane of the common base portion and said one arm.

References Cited by the Examiner UNITED STATES PATENTS Re. 21,547 9/1940 Bessey 339258 X 1,582,957 5/1926 Avery 339-63 1,791,264 2/1931 Chaney et al 33914 2,157,428 5/1939 Obszarny 339220 X 2,694,188 11/1954 Poupitch 339-258 X 2,993,189 7/1961 Schelke et al 339-14 X 3,052,864 9/1962 Gaynor 339-258 X FOREIGN PATENTS 1,061,409 7/1959 Germany.

r JOSEPH D. SEERS, Primary Examiner.

PATRICK A. CLIFFORD, Examiner. 

1. A GROUNDING WIRE FEMALE CONNECTOR ADAPTED TO RECEIVE EITHER A PARALLEL BLADE OR A TANDEN BLADE PLUG, COMPRISING AN INSULATING HOUSING HAVING THREE LONGITUDINALLY EXTENDING, PARALLEL CHANNELS PARTITIONED FROM EACH OTHER IN A LATERAL DIRECTION, A SINGLE PIECE ELONGATED METAL CONTACT DISPOSED IN EACH OF SAID CHANNELS, ONE OF SAID CONTACTS ENGAGEABLE WITH A PLUG GROUNDING PRONG AND HAVING A PAIR OF SPACED APART, FLAT, ELONGATED RESILIENT ARMS EXTENDING LONGITUDINALLY FROM A COMMON METAL BASE PORTION WITH THE WIDTH DIMENSION OF SAID ARMS DISPOSED IN A COMMON PLANE, EACH ARM HAVING RESPECTIVE END CONTACT SURFACES FORMED GENERALLY AT RIGHT ANGLES TO THE WIDTH DIMENSION AND CONFRONTING EACH OTHER IN SPACED RELATION FOR ENGAGING SAID GROUNDING PRONG THEREBETWEEN, EACH OF THE OTHER TWO METAL CONTACTS HAVING THREE, SPACED APART RESILIENT CONTACT ARMS EXTENDING LONGITUDINALLY FROM A COMMON METAL BASE PORTION, ON ARM BEING GENERALLY COPLANAR WITH SAID BASE PORTION, THE OTHER TWO ARMS BEING GENERALLY PERPENDICULAR WITH SAID BASE PORTION AND SAID ONE ARM, AND PARALLEL WITH EACH OTHER, SAID TWO ARMS HAVING EXTENSIONS PROJECTING INWARDLY TOWARDS EACH OTHER IN A SPACED BUT CONFRONTING RELATION TO EACH OTHER AND TO SAID ONE ARM TO FORM A POWER CONTACT CHANNEL FOR RECEIVING A PARALLEL BLADE OR A TANDEM BLADE, SAID TANDEM BLADE PARTIALLY ENGAGED BY THE CONFRONTING EXTENSIONS AND SAID ONE ARM IN SUBSTANTIALLY PERPENDICULAR DIRECTION THERETO, SAID PARALLEL BLADE TOTALLY ENGAGED INSIDE THE CHANNEL IN A PLANE SUBSTANTIALLY PARALLEL TO THE EXTENSIONS AND TO SAID ONE ARM, SAID TWO INWARDLY PROJECTING ARM EXTENSIONS AND SAID ONE ARM FIRMLY ENGAGING EITHER TYPES OF BLADE SO AS TO FORCE THE EXTENSIONS AND ARM AGAINST EACH OTHER. 